Using qualitative evidence to identify factors influencing ICU health carers' use of guidelines to take adults and children off mechanical ventilation


Many critically-ill adults and children being cared for in an intensive care unit (ICU) are unable to breathe by themselves. When this happens they are put on a mechanical ventilator, a machine that helps them to breathe. Staying on a ventilator for too long increases the likelihood of harmful effects, including trauma and infection of the lungs and complications of prolonged immobility such as blood clots in the legs or lungs. Consequently, researchers have tried to find ways to take people off ventilators (that is, to wean them) as soon as is safely possible. One way is by using guidelines, or protocols. Two recent Cochrane reviews combined evidence from different research studies. Some studies showed that protocols were successful in reducing the amount of time spent on a ventilator, while other studies showed that using protocols did not make any difference to the amount of time spent on a ventilator. These contrasting findings could have been caused by a range of factors. Researchers investigating these factors have used qualitative research methods, which usually involve talking to people or observing how people behave, or both.

Review question

What are the factors influencing how healthcare professionals use protocols to wean adults and children from mechanical ventilation?


To identify studies using qualitative methods, we searched relevant electronic databases of journals in February 2015. We also searched the reference lists of articles, contacted the authors of all of the studies included in the two earlier reviews and in our qualitative synthesis, and contacted experts in mechanical ventilation. We combined the findings of the relevant studies to produce a synthesis of the evidence on what influences health professionals to use protocols. We then combined our synthesis with the findings of the two earlier reviews to help explain why some of the studies had shown protocols to be effective and others had not. We were able to do so by producing explanations of how different factors work together to either promote or hinder the use of protocols. We outlined these explanations in a ‘logic model’.

Key findings

Our synthesis included 11 studies, involving around 267 participants; five more studies are awaiting classification. We identified several potential barriers and facilitators to the use of protocols. First, doctors used protocols only in certain circumstances; otherwise they preferred to wean using their own knowledge and skills. Relatively inexperienced nurses often lacked confidence. A protocol could encourage their involvement in weaning because it set out clear instructions and also helped them to feel more secure. Although more experienced nurses also recognized these positive qualities, they criticized protocols as sometimes instructing them to wean contrary to their own clinical judgement. Second, the practical arrangements for care within an ICU could either help or hinder healthcare professionals to work together, and in this way influence how (well) a protocol was used. Third, the use of a protocol reflected how healthcare professionals interact with one another generally. For example, the degree of experience a nurse or doctor possessed could influence the confidence others had that they could wean safely. For this reason, doctors tended to be reluctant to involve nurses they considered to be relatively inexperienced in weaning, even when there was a protocol in place. Furthermore, the fact that doctors occupied a higher professional status or position meant that it was difficult for nurses to be involved in weaning, including by using a protocol, unless the doctors s/he worked with permitted this to happen.

Quality of the evidence

We developed 35 summary statements. Of these: we assessed 17 statements as ‘low’ confidence, largely because the evidence used to develop them came from only a small number of studies. We rated 13 statements as ‘moderate’ confidence, largely because the evidence used to develop them came from very well-conducted studies, and we rated five statements as ‘high’ confidence, largely because the evidence used to develop them came from a majority of the studies.

Authors' conclusions: 

There is a clear need for weaning protocols to take account of the social and cultural environment in which they are to be implemented. Irrespective of its inherent strengths, a protocol will not be used if it does not accommodate these complexities. In terms of protocol development, comprehensive interprofessional input will help to ensure broad-based understanding and a sense of ‘ownership’. In terms of implementation, all relevant ICU staff will benefit from general weaning as well as protocol-specific training; not only will this help secure a relevant clinical knowledge base and operational understanding, but will also demonstrate to others that this knowledge and understanding is in place. In order to maximize relevance and acceptability, protocols should be designed with the patient profile and requirements of the target ICU in mind. Predictably, an under-resourced ICU will impact adversely on protocol implementation, as staff will prioritize management of acutely deteriorating and critically-ill patients.

Read the full abstract...

Prolonged mechanical ventilation is associated with a longer intensive care unit (ICU) length of stay and higher mortality. Consequently, methods to improve ventilator weaning processes have been sought. Two recent Cochrane systematic reviews in ICU adult and paediatric populations concluded that protocols can be effective in reducing the duration of mechanical ventilation, but there was significant heterogeneity in study findings. Growing awareness of the benefits of understanding the contextual factors impacting on effectiveness has encouraged the integration of qualitative evidence syntheses with effectiveness reviews, which has delivered important insights into the reasons underpinning (differential) effectiveness of healthcare interventions.


1. To locate, appraise and synthesize qualitative evidence concerning the barriers and facilitators of the use of protocols for weaning critically-ill adults and children from mechanical ventilation;

2. To integrate this synthesis with two Cochrane effectiveness reviews of protocolized weaning to help explain observed heterogeneity by identifying contextual factors that impact on the use of protocols for weaning critically-ill adults and children from mechanical ventilation;

3. To use the integrated body of evidence to suggest the circumstances in which weaning protocols are most likely to be used.

Search strategy: 

We used a range of search terms identified with the help of the SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) mnemonic. Where available, we used appropriate methodological filters for specific databases. We searched the following databases: Ovid MEDLINE, Embase, OVID, PsycINFO, CINAHL Plus, EBSCOHost, Web of Science Core Collection, ASSIA, IBSS, Sociological Abstracts, ProQuest and LILACS on the 26th February 2015. In addition, we searched: the grey literature; the websites of professional associations for relevant publications; and the reference lists of all publications reviewed. We also contacted authors of the trials included in the effectiveness reviews as well as of studies (potentially) included in the qualitative synthesis, conducted citation searches of the publications reporting these studies, and contacted content experts.

We reran the search on 3rd July 2016 and found three studies, which are awaiting classification.

Selection criteria: 

We included qualitative studies that described: the circumstances in which protocols are designed, implemented or used, or both, and the views and experiences of healthcare professionals either involved in the design, implementation or use of weaning protocols or involved in the weaning of critically-ill adults and children from mechanical ventilation not using protocols. We included studies that: reflected on any aspect of the use of protocols, explored contextual factors relevant to the development, implementation or use of weaning protocols, and reported contextual phenomena and outcomes identified as relevant to the effectiveness of protocolized weaning from mechanical ventilation.

Data collection and analysis: 

At each stage, two review authors undertook designated tasks, with the results shared amongst the wider team for discussion and final development. We independently reviewed all retrieved titles, abstracts and full papers for inclusion, and independently extracted selected data from included studies. We used the findings of the included studies to develop a new set of analytic themes focused on the barriers and facilitators to the use of protocols, and further refined them to produce a set of summary statements. We used the Confidence in the Evidence from Reviews of Qualitative Research (CERQual) framework to arrive at a final assessment of the overall confidence of the evidence used in the synthesis. We included all studies but undertook two sensitivity analyses to determine how the removal of certain bodies of evidence impacted on the content and confidence of the synthesis. We deployed a logic model to integrate the findings of the qualitative evidence synthesis with those of the Cochrane effectiveness reviews.

Main results: 

We included 11 studies in our synthesis, involving 267 participants (one study did not report the number of participants). Five more studies are awaiting classification and will be dealt with when we update the review.

The quality of the evidence was mixed; of the 35 summary statements, we assessed 17 as ‘low’, 13 as ‘moderate’ and five as ‘high’ confidence. Our synthesis produced nine analytical themes, which report potential barriers and facilitators to the use of protocols. The themes are: the need for continual staff training and development; clinical experience as this promotes felt and perceived competence and confidence to wean; the vulnerability of weaning to disparate interprofessional working; an understanding of protocols as militating against a necessary proactivity in clinical practice; perceived nursing scope of practice and professional risk; ICU structure and processes of care; the ability of protocols to act as a prompt for shared care and consistency in weaning practice; maximizing the use of protocols through visibility and ease of implementation; and the ability of protocols to act as a framework for communication with parents.